System and method for indicating local IP access support via NAS signaling

ABSTRACT

A method of providing Local IP Access (LIPA) indication is proposed. In one novel aspect, an enhanced cell selection method is proposed using LIPA capability information. Based on LIPA capability related information, a UE is able to prioritize LIPA-capable cells and establish a corresponding packet data network (PDN) connection accordingly. In one embodiment, LIPA information is informed to the UE via Non Access Stratum (NAS) signaling. The UE stores LIPA capability information when receiving a NAS message from a mobility management entity (MME). Later on, when the UE performs cell selection or reselection in idle mode, the UE can use the stored LIPA capability information to prioritize LIPA-capable cells.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 from U.S.Provisional Application No. 61/504,557, entitled “Indication of LIPASupport,” filed on Jul. 5, 2011, the subject matter of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to mobile communication systemsand, more particularly, to providing local IP access in 3GPP LTE/LTE-Asystems.

BACKGROUND

The 3^(rd) Generation Partnership Project (3GPP) is investigatingEvolved Packet System (EPS) as a next generation mobile communicationsystem, and studying Home eNodeB (HeNB) as a small base stationinstalled for local cell coverage. Home base stations are base stationsdesigned to serve relatively small geographic areas and are widelydeployed at various locations such as homes, offices, shops, andapartments, etc. These home base stations are often used to improveindoor radio coverage, increase throughput, reduce load onmacro-cellular networks, and/or provide other benefits for networkoperators and/or users. Unlike macro base stations that are carefullydeployed at specific locations and maintained by network operators, homebase stations may be flexibly deployed in an unplanned manner at anylocation by users.

In 3GPP, local IP access (LIPA) support is defined as a functionalrequirement for a home base station. LIPA provides IP capable UEsconnectivity to a local IP network, such as an IP network inside a hometo which the home base station is connected. For example, LIPA enables aUE to connect to another terminal (e.g., a local printer) that is partof the home network without passing through the mobile operator's corenetwork. Conventionally, if a UE wants to connect to a local printerthat has no cellular interface, then the UE needs to use a localcommunication interface such as a wireless LAN. The use of LIPA enablesa UE to use a cellular communication interface to communicate with otherterminals within the home network because the home base stationfunctions as a gateway between different wireless access technologies.

Once a Packet Data Network (PDN) connection is established for LIPAtransmission, data traffic is directed to the home network, and the homebase station forwards the data traffic without passing through themobile operator's core network. However, signaling traffic will continueto traverse the mobile operator's core network. 3GPP has defined certainrequirements for LIPA. First, a user may be notified when a home basestation provides access to a residential or enterprise IP network.Second, the mobile operator shall be able to configure the home basestation to enable or disable local IP access. Third, the mobile operatorshall be able to enable or disable local IP access per user subscriptionper Closed Subscriber Group (CSG). Each home base station is associatedwith a CSG cell having a CSG identifier. Whether or not a user ispermitted to access a CSG cell is determined based on the user'ssubscription information.

In 3GPP TR 23.829 and TR 23.859, indications to UEs on whether a PDNconnection for LIPA traffic can be initiated and/or on the Access PointName (APN) to request were discussed. Possible solutions are via UEconfiguration, NAS signaling, or RRC signaling. However, the details ofthe options are still unclear. In this patent application, detaildesigns for various possible methods of providing LIPA indication areproposed.

SUMMARY

A method of providing Local IP Access (LIPA) indication is proposed. Inone novel aspect, an enhanced cell selection method is proposed usingLIPA capability information. Based on LIPA capability relatedinformation, a UE is able to prioritize LIPA-capable cells and establisha corresponding packet data network (PDN) connection accordingly.

In a first embodiment, LIPA information is statically configured in theUE. In one example, a list of CSG IDs and PCI range information per CSGID having LIPA support is delivered to a UE via an Over the Air (OTA)protocol, such as via Open Mobile Alliance (OMA) Device Management (DM)protocol.

In a second embodiment, LIPA information is informed to the UE viabroadcasting or unicasting Radio Resource Control (RRC) signaling. Forbroadcasting method, the UE obtains CSG ID and LIPA capabilityinformation of a cell by reading system information (e.g., SIB1)broadcasted by eNB. For unicasting method, in a first option, eNBindicates the support of LIPA in an RRC connection setup message. In asecond option, UE indicates the preference of LIPA in an RRC connectionrequest message. If eNB does not support LIPA, it may redirect the UE toa LIPA-capable cell by handover or connection release/rejection withLIPA redirect information.

In a third embodiment, LIPA information is informed to the UE via NonAccess Stratum (NAS) signaling. The general idea of the NAS-basedsignaling method for LIPA indication is that “the support of LIPA”information is provided to UE by a mobility management entity (MME) viaa NAS message after an RRC connection is established for the UE. The UEthen stores the LIPA capability information when receiving the NASmessage from MME. Later on, when the UE performs cell selection orreselection in idle mode, the UE can use the stored LIPA capabilityinformation to prioritize the LIPA-capable cells.

Other embodiments and advantages are described in the detaileddescription below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like numerals indicate like components,illustrate embodiments of the invention.

FIG. 1 illustrates a mobile wireless communication network that supportslocal IP access in accordance with one novel aspect.

FIG. 2 illustrates a simplified block diagram of a user equipment inaccordance with one novel aspect.

FIG. 3 illustrates a first method of providing LIPA indication via UEconfiguration.

FIG. 4 illustrates one embodiment of providing LIPA indication accordingto the first method of UE configuration in a mobile communicationnetwork.

FIG. 5 illustrates one embodiment of providing LIPA indication via asecond method of RRC signaling in a mobile communication network.

FIG. 6 illustrates another embodiment of providing LIPA indication via asecond method of RRC signaling in a mobile communication network.

FIG. 7 is a flow chart of a method of providing LIPA indication fromuser equipment aspect in accordance with one novel aspect.

FIG. 8 is a flow char of a method of providing LIPA indication from basestation aspect in accordance with one novel aspect.

FIG. 9 illustrates a third method of providing LIPA indication via NASsignaling.

FIG. 10 illustrates one embodiment of providing LIPA indicationaccording to the third method of NAS signaling in a mobile communicationnetwork.

FIG. 11 illustrates another embodiment of providing LIPA indicationaccording to the third method of NAS signaling in a mobile communicationnetwork.

FIG. 12 is a flow chart of a method of providing LIAP indication via NASsignaling.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 1 illustrates a mobile communication network 100 that supportslocal IP access (LIPA) in accordance with one novel aspect. Mobilecommunication network 100 comprises a user equipment (UE) 101 and a homeeNodeB (H(e)NB or HeNB) 102 that provides radio access to a mobileoperator core network (CN) 110. H(e)NB 102 is also part of a localresidential or enterprise IP network 120, which includes a local printer121, a local monitor 122, and a local computer server 123. In theexample of FIG. 1, UE 101 is an IP capable UE, and H(e)NB 102 providesLIPA for UE 101 to connect to other IP entities (e.g., printer 121) inthe same local IP network 120, which are all located inside home 130.

In general, LIPA provide access for IP capable UEs connected via H(e)NB(i.e., using H(e)NB radio access) to other IP capable entities in thesame residential or enterprise IP network. This kind of behavior iscalled local IP breakout, where the IP packet is redirected via local IPserver. LIPA is one of the protocols to implement local IP breakout.3GPP has defined certain requirements for LIPA. First, a user may benotified when a home base station provides access to a residential orenterprise IP network. Second, the mobile operator shall be able toconfigure the home base station to enable or disable local IP access.Third, the mobile operator shall be able to enable or disable local IPaccess per user subscription per Closed Subscriber Group (CSG). Eachhome station is associated with a CSG cell having a CSG identifier (CSGID). Whether or not a user is permitted to access a CSG cell isdetermined based on the user's subscription information.

In one novel aspect, an enhanced cell selection method is proposed usingLIPA capability information. Based on LIPA capability relatedinformation, a UE is able to prioritize LIPA-capable cells and establisha corresponding packet data network (PDN) connection accordingly. FIG. 1illustrates three different embodiments of providing LIPA information140 to UE 101 for enhanced cell selection. In a first embodiment, LIPAinformation is statically configured in the UE based on provisioning. Ina second embodiment, LIPA information is informed to the UE viabroadcasting or unicasting Radio Resource Control (RRC) signaling. In athird embodiment, LIPA information is informed to the UE via Non AccessStratum (NAS) signaling.

FIG. 2 illustrates a simplified block diagram of a user equipment UE 201in accordance with one novel aspect. UE 201 comprises memory 211, aprocessor 212, a radio frequency (RF) module 213 coupled to antenna 214,a baseband module 215, a 3GPP protocol stack module 226 supportingvarious protocol layers including NAS 225, RRC 224, PDCP/RLC 223, MAC222 and PHY 221, a TCP/IP protocol stack module 227, and a managementmodule 230 including a user interface (UI) module 231, a cell(re)selection module 232, a handover (HO) module 233, and aconfiguration module 234. The various modules are function modules andmay be implemented by software, firmware, hardware, or any combinationthereof. The function modules, when executed by processor 212 (viaprogram instructions contained in memory 211), interwork with each otherto allow UE 201 to perform cell (re)selection and establish PDNconnection based on LIPA information. For example, NAS 225 processesreceived NAS signaling such that the UE can store LIPA informationcontained in the NAS message. Cell selection module 232 then uses thestored LIPA information to prioritize LIPA-capable cells.

FIG. 3 illustrates a first method of providing LIPA indication via UEconfiguration in a mobile communication network 300. Mobilecommunication network 300 comprises a UE 301, an H(e)NB 302, an OpenMobile Alliance (OMA) Device Management (DM) server 303, and a mobileoperator's core network CN 310. Under the UE configuration method, theLIPA information is delivered by an Over the Air (OTA) protocol to UE301. In the example of FIG. 3, OMA DM server 303 is used to deliver theLIPA information to UE 301. LIPA information typically includes LIPAcapability of a HeNB, i.e., whether LIPA is supported by the HeNB.

An important aspect of H(e)NB functionality is the ability to restrictaccess to particular users. For example, access is limited to employeesof a company on whose site the HeNB is deployed, to customers of aparticular coffee shop chain, or (in the case of HeNBs deployed inprivate homes) to individuals. To achieve this functionality, 3GPP hasdefined the concept of CSG. When a cell is configured in CSG mode, onlythose users included in the cell's access control list are allowed toaccess the cell. When a UE subscribes to a CSG cell, the UE is thenincluded in the CGS cell's access control list. A subscription may betemporary in nature (e.g. a coffee shop allows a customer one hour'saccess to its CSG cell). The CSG cell indicates that the HeNB is a CSGcell via system information broadcasting. The CSG cell also broadcasts aCSG ID via system information.

Under the UE configuration method, LIPA capability information may bestatically configured in UE and stored in UE's Subscriber IdentityModule or Universal Subscriber Identity Module (SIM/USIM). For example,a list of CSG IDs having LIPA support is statically configured in the UEbased on provisioning. This method best suits the case for residentialLIPA support. For enterprise deployment, it also makes sense that thesupport of LIPA of HeNB is statically configured. Therefore, the LIPAcapability of HeNBs can be known in advance under this method.Furthermore, the configured information can be encrypted and protected.

This UE configuration method, however, cannot be applied to a scenariothat not all HeNBs in an enterprise network support LIPA. In a corporatenetwork, for example, it is possible that some of the HeNBs support LIPAwhile others do not. If the UE configuration is defined per CSG ID andnot per HeNB, then the UE cannot identify whether a specific HeNBsupports LIPA. To solve the UE configuration problem, it is proposedthat LIPA capability of a specific HeNB is added as additionalinformation attached to the list of CSG IDs. For example, Physical CellID (PCI) range information is provided per CSG ID to indicate thesupport of LIPA. Currently, a set of PCI ranging is already reserved forCSG-only cells and the PCI of each CSG cell can be configured by OAM. Asillustrated in FIG. 3, LIPA information 320 delivered from OMA DM server303 to UE 301 contains LIPA capability, a list of CSG IDs, and PCI rangeinformation for each CSG ID.

FIG. 4 illustrates one embodiment of providing LIPA indication accordingto the first method of UE configuration in a mobile communicationnetwork. In step 411, UE 401 receives an OMA DM configuration from OMADM server 403. The OMA DM configuration may occur at any time, i.e.,when UE 401 is in RRC_IDLE or RRC_Connected mode. The OMA DMconfiguration contains LIPA information, which includes LIPA capability,a list of CSG IDs, and a set of PCI ranging for each CSG. In step 412,UE 401 stores the LIPA information in SIM/USIM. In step 413, UE performscell selection in idle mode. The stored LIPA information may be used toprioritize LIPA-capable cells. For example, HeNB 402 serves aLIPA-capable cell, which is selected by UE 401. In step 414, UE 401establishes a RRC connection with HeNB 402. In step 415, UE 401establishes a LIPA PDN connection with MME 404 as part of a Non AccessStratum (NAS) connection to set up a connection bearer with a mobilitymanagement entity (MME).

The first method of providing LIPA indication via UE configurationsupport both cell selection and cell reselection based on LIPAcapability information. The method has no RAN impacts. However, thecurrent Allowed CSG list MO defined in TS24.285 does not allowindication per H(e)NB. Therefore, this method has OAM impacts. New leafneeds to be defined in the Allowed CSG list and Operator CSG list foreach CSG entry.

A second method of providing LIPA indication is via RRC signaling. Thesupport of LIPA capability can be carried in broadcasting or unicastingfashion. For broadcasting method, the support of LIPA capability isbroadcasted via System Information Block (e.g., SIB1). For unicastingmethod, the support of LIPA capability is indicated via dedicated RRCsignaling.

FIG. 5 illustrates one embodiment of providing LIPA indication via RRCbroadcasting in a mobile communication network. In step 511, UE 501starts to perform cell selection and tries to select a cell with thebest link quality and/or other preferences (e.g., LIPA capability). Instep 512, UE 501 reads SIB1 that is broadcasted from base station eNB502. SIB1 contains CSG ID and LIPA capability information of a cellserved by eNB 502, which helps UE 501 to make a preferred choice duringthe cell selection process. For example, UE 501 checks the contents ofSIB1. If UE 501 belongs to the CSG (e.g., based on the CSG ID) and thecell indicates the support of LIPA, then this candidate cell is selectedwith higher priority. In step 513, UE 501 established an RRC connectionwith a selected LIPA-capable cell served by eNB 502. Finally, in step514, UE 501 establishes a LIPA PDN connection with MME 503.

FIG. 6 illustrates one embodiment of providing LIPA indication viadedicated RRC signaling in a mobile communication network. In step 611,UE 601 starts to perform cell selection and tries to select a cell withthe best link quality and/or other preferences (e.g., LIPA capability).UE 601, however, may not have any LIPA capability information at thispoint. In step 612, UE 601 selects a cell served by eNB1 602 andtransmits a RRC connect request to eNB1 602. The RRC connect requestindicates the preference for LIPA support. Upon receiving the RRCconnect request, if eNB1 602 supports LIPA, then it may reply with a RRCconnect setup back to UE 601 to establish a RRC connection. In theexample of FIG. 6, however, eNB1 602 does not support LIPA. As a result,eNB1 602 redirects UE 601 to another LIPA-capable cell by handoverprocedure or connection release/reject with LIPA redirectioninformation. For example, in step 613, eNB1 602 transmits a RRC connectreject message to UE 601. The RRC connect reject message contains LIPAredirection information, such as the physical cell ID of a LIPA-capablecell served by eNB2 603. In step 614, UE 601 transmits another RRCconnect request to eNB2 603. The RRC connect request again indicates thepreference for LIPA support. In step 615, eNB2 603 replies with a RRCconnect setup back to UE 601. The RRC connect setup message indicatesthe support of LIPA. Finally, in step 616, UE 601 and MME 604 establisha LIPA PDN connection.

The second method of providing LIPA indication via RRC signaling has RANimpact. For broadcasting method, it supports both cell selection andcell reselection based on LIPA capability if the LIPA capabilityinformation is indicated by SIB1. For unicasting method, the eNB canindicate the support of LIPA, or the UE can indicate the preference ofLIPA. However, RRC message (both broadcasting and unicasting) needsmodification to convey the LIPA indication.

FIG. 7 is a flow chart of a method of providing LIPA indication fromuser equipment aspect in accordance with one novel aspect. In step 701,a UE performs cell selection in a mobile communication network. The UEperforms various measurements over different cells so that the UE canselect a cell with the best link quality. In step 702, the UE obtainsLIPA information of one or multiple cells including LIPA capability andassociated CSG IDs. Note that step 702 may be performed before step 701.In one example, the UE receives LIPA information from an OTA protocol(e.g., from an OMA DM server) and then stores the information inSIM/USIM before the cell selection. In another example, the UE readsLIPA information broadcasted via SIB1. The UE is then able to prioritizeLIPA-capable cells during the cell selection. In step 703, the UEestablishes a RRC connection in a selected LIPA-capable cell with aHeNB. In step 704, the UE established a LIPA PDN connection in theselected LIPA-capable cell with an MME.

FIG. 8 is a flow chart of a method of providing LIPA indication frombase station aspect in accordance with one novel aspect. In step 801, ahome base station HeNB receives a RRC connect request message from a UEin a mobile communication network. The RRCConnectionRequest messageindicates the preference of LIPA support. In step 802, the HeNBtransmits a RRC connection setup message to the UE. TheRRCConnectionSetup message indicates whether LIPA is supported. In step803, the HeNB establishes a LIPA PDN connection with the UE if the HeNBsupports LIPA. Alternatively, in step 804, if the HeNB does not supportLIPA, then the HeNB redirects the UE to another cell by handover or byconnection release/reject with LIPA redirect information.

FIG. 9 illustrates a third method of providing LIPA indication via NASsignaling in a mobile communication network 900. Mobile communicationnetwork 900 comprises a radio access network (RAN) 910, an evolvedpacket core (EPC) 920, and a mobile operator's data network or theInternet 930. The radio access network 910 comprises a user equipment UE911, a macro base station MeNB 912, and a home base station HeNB 913.Evolved packet core 920 comprises a mobility management entity MME 921,a serving gateway (S-GW) 922, and a packet data network gateway (PDN-GW)923. In mobile communication network 900, the radio access network 910provides cellular access for UE 911 to access mobile operator's datanetwork and/or the Internet 930 via the evolved packet core 920 (e.g.,as depicted by a long-dashed line 931).

The home base station HeNB 913, however, is also part of a local IPnetwork 940. Therefore, if the HeNB has LIPA capability, then HeNB 913can provide LIPA for UE 911 to directly communicate with other IPdevices in the local IP network 940 (e.g., as depicted by a short-dashedline 941). Once a LIPA PDN connection is established for UE 911 throughHeNB 913, the data traffic does not traverse through the evolved packetcore network 920, while the signaling traffic continue to traversethrough the evolved packet core network 920.

In general, the NAS layer can provide information to instruct cellselection performed in the AS layer. The NAS layer controls cellselection, for example, by indicating the preference of RAT(s)/cellsassociated with the selected PLMN to be used initially in the search ofa cell. NAS also maintains lists of forbidden registration areas and alist of CSG IDs and their associated PLMN ID on which the UE is allowed(CSG white list) and provide these lists to AS layer. On the other hand,the UE AS layer searches for a suitable cell and perform measurementsneeded to support cell selection.

Therefore, the general idea of the NAS-based signaling method for LIPAindication is that “the support of LIPA” information is provided to UE911 by MME 921 via a NAS message after an RRC connection is establishedfor UE 911. The problem of such method is that a UE may only be aware ofLIPA support after it establishes an RRC connection and receives a NASmessage. Because the LIPA capability is static information for HeNB, itis thus proposed that UE 911 stores the LIPA information when receivingthe NAS message from MME 921. Later on, when UE 911 performs cellselection in idle mode, UE 911 can use the stored LIPA capabilityinformation to prioritize the LIPA-capable cells. One advantage of theNAS signaling method is that it is up to the UE implementation to storeand utilized the LIPA capability information, as long as suchinformation is known by the MME/SGSN and provided to the UE via a NASmessage.

FIG. 10 illustrates one embodiment of providing LIPA indicationaccording to the third method of NAS signaling in a mobile communicationnetwork. In step 1011, UE 1001 first establishes an RRC connection witha macro base station MeNB 1002. Afterwards, UE 601 receives a NASmessage from MME 1004 (step 1012). The NAS message specifies a list ofLIPA-capable cells with the same CSG ID. Note that, CSG ID is anidentification of a group of cells sharing the same access control list.In step 1013, UE 1001 stores the received LIPA information. Later on, UE1001 goes back to idle mode. In step 1015, UE 1001 performs cellselection in idle mode. The stored LIPA information may be used toprioritize LIPA-capable cells. For example, HeNB 1003 serves aLIPA-capable cell having the same CSG ID, which is then selected by UE1001. In step 1016, UE 601 establishes a RRC connection with HeNB 1003.In step 1017, UE 1001 establishes a LIPA PDN connection with MME 1004 aspart of a NAS connection to set up a connection bearer.

FIG. 11 illustrates another embodiment of providing LIPA indicationaccording to the third method of NAS signaling in a mobile communicationnetwork. In step 1111, UE 1110 first establishes an RRC connection witha first home base station HeNB1 1101. Afterwards, UE 1110 receives a NASmessage from MME 1104 (step 1112). The NAS message specifies LIPAcapability of the cell. In one embodiment, NAS message specifies a listof LIPA-capable cells with the same CSG ID. Note that, CSG ID is anidentification of a group of cells sharing the same access control list.In step 1113, UE 1110 stores the received LIPA information as historicaldata. NAS layer only indicates the LIPA capability of the current cell.However, UE can collect the LIPA information for all the cells that itcamped before. Later on, a radio link failure (RLF) event occurred (step1114). In step 1115, UE 1110 performs cell reselection in idle mode. Thestored LIPA information may be used to prioritize LIPA-capable cells.For example, a second home base station HeNB2 1102 does not supportLIPA; while a third home base station HeNB3 1103 does support LIPA. Forexample, HeNB3 1103 serves a LIPA-capable cell having the same CSG ID,which is then selected by UE 1001. In step 1116, UE 1110 establishes aRRC connection with HeNB3 1103. In step 1117, UE 1110 establishes a LIPAPDN connection with MME 1104 as part of a NAS connection to set up aconnection bearer. Note that, the RLF-triggered is one of the examplesof cell reselection. In one embodiment, cell reselection is triggered byconnection release (or reject) with cell redirection information. UE canperform cell reselection by considering the redirection information andthe stored LIPA-capable cell information.

FIG. 12 is a flow chart of a method of providing LIAP indication via NASsignaling in accordance with one novel aspect. In step 1201, a UEobtains LIPA information in a mobile communication network. In oneexample, the LIPA information is contained in a NAS message from an MMEin the mobile communication network. The UE stores the LIPA informationsuch that it is then able to prioritize LIPA-capable cells during cell(re)selection. In step 1202, the UE performs cell selection or cellreselection. The UE performs various measurements over different cellsso that the UE can select a cell with the best link quality. The UE alsotake into account which cell is LIPA-capable. In step 1203, the UEestablishes a RRC connection in a selected LIPA-capable cell with aHeNB. In step 1204, the UE established a LIPA PDN connection in theselected LIPA-capable cell with an MME.

In general, if less RAN impact is the design goal, then the method of UEconfiguration or NAS signaling can be applied. UE can get somepreferences (e.g., LIPA-capable cells) from higher layer beforeperforming cell selection or cell reselection. Thus, the proposedmethods can be viewed as a cell (re)selection enhancement. The NAS andRRC LIPA indication can be independent (e.g., co-exist). The RRCsignaling can be used to reveal LIPA support in AS level, while the NASsignaling can be used to transmit a list of LIPA supported HeNBs orCSGs.

Although the present invention has been described in connection withcertain specific embodiments for instructional purposes, the presentinvention is not limited thereto. Accordingly, various modifications,adaptations, and combinations of various features of the describedembodiments can be practiced without departing from the scope of theinvention as set forth in the claims.

What is claimed is:
 1. A method comprising: obtaining Local IP Access(LIPA) capability information by a user equipment (UE) in a mobilecommunication network, wherein the LIPA capability information isobtained via a Non Access Stratum (NAS) message from a MobilityManagement Entity (MME), and wherein the NAS message is received afterestablishing a first radio resource control (RRC) connection; detectinga cell selection or cell reselection trigger event and entering an idlemode; performing cell selection or cell reselection by the UE based atleast in part on the obtained LIPA capability information; establishinga second radio resource control (RRC) connection with a selected cell;and establishing a LIPA packet data network (PDN) connection with theselected cell.
 2. The method of claim 1, wherein the cell (re) selectionis selectively determined by the obtained LIPA capability information.3. The method of claim 1, wherein a LIPA-capable cell is prioritizedover a non-LIPA-capable cell during the cell (re)selection.
 4. Themethod of claim 1, wherein the LIPA capability information comprises aClosed Subscriber Group (CSG) ID and a list of LIPA-supportedHome-eNodeB (HeNB) cell IDs belonging to the same CSG ID.
 5. The methodof claim 1, wherein the trigger event is a radio link failure (RLF)event.
 6. The method of claim 1, wherein the trigger event is receivinga connection release message with redirection information by the UE. 7.A user equipment (UE), comprising: memory that contains a set of programinstructions; and a processor that executes the set of programinstructions and thereby manipulates the UE to perform the steps of:obtaining Local IP Access (LIPA) capability information by in a mobilecommunication network, wherein the LIPA capability information isobtained via a Non Access Stratum (NAS) message from a MobilityManagement Entity (MME), and wherein the NAS message is received afterestablishing a first radio resource control (RRC) connection; detectinga cell selection or cell reselection trigger event and entering an idlemode; performing cell selection or cell reselection by the UE based atleast in part on the obtained LIPA capability information, establishinga second radio resource control (RRC) connection with a selected cell;and establishing a LIPA packet data network (PDN) connection with theselected cell.
 8. The UE of claim 7, wherein the LIPA capabilityinformation comprises a Closed Subscriber Group (CSG) ID and a list ofLIPA-supported Home-eNodeB (HeNB) cell IDs belonging to the same CSG ID.9. The UE of claim 7, wherein the cell (re) selection is selectivelydetermined by the obtained LIPA capability information.
 10. The UE ofclaim 7, wherein a LIPA-capable cell is prioritized over anon-LIPA-capable cell during the cell (re)selection.
 11. The UE of claim7, wherein the trigger event is a radio link failure (RLF) event. 12.The UE of claim 7, wherein the trigger event is receiving a connectionrelease message with redirection information by the UE.